Engine components in the hot gas flow of modern combustion turbines are required to operate at ever-increasing temperatures as engine efficiency requirements continue to advance. Ceramics typically have higher heat tolerance and lower thermal conductivities than metals, particularly in the case of oxide-based ceramic materials. For this reason, ceramics have been used both as structural materials in place of metallic materials and as coatings for both metal and ceramic structures. Ceramic matrix composite (CMC) wall structures with ceramic insulation outer coatings, such as described in commonly owned U.S. Pat. No. 6,197,424, have been developed to provide components with the high temperature stability of ceramics without the brittleness of monolithic ceramics.
The versatility of an insulated CMC material may be influenced by the strength of the bond between the insulation and the structural CMC material. For example, some environments and/or engine components may require an incremental bonding strength relative to baseline bond strength. Accordingly, further improvements that increment the bonding strength between the insulation and the structural CMC material are desired.